Depth of field for a camera in a media-editing application

ABSTRACT

Some embodiments provide a method that provides tools for defining a scene including media objects in a multi-dimensional space. The method provides a set of user interface tools for adjusting a region of focus for rendering the space from a particular location within a particular field of view. In some embodiments, the region of focus is a first region in the space within the particular field of view and the space further includes a second region outside of the region of focus within the particular field of view. In some embodiments, the method also provides a set of effects for applying to the second region but not the first region to visually indicate the first region as the region of focus within the space and the second region as a region outside of the region of focus within the space.

INCORPORATION BY REFERENCE; DISCLAIMER

Each of the following applications are hereby incorporated by reference:application Ser. No. 16/434,062 filed on Jun. 6, 2019, application Ser.No. 13/472,214 filed on Mar. 28, 2017 and application Ser. No.12/245,698, filed Oct. 3, 2008. The Applicant hereby rescinds anydisclaimer of claim scope in the parent application(s) or theprosecution history thereof and advises the USPTO that the claims inthis application may be broader than any claim in the parentapplication(s).

FIELD OF THE INVENTION

The invention is directed towards image and video rendering.Specifically, the invention is directed towards depth of fieldproperties for cameras in applications that render images and/or videos.

BACKGROUND OF THE INVENTION

Digital graphic design, video editing, and media editing applicationsprovide designers and artists with tools to create much of the mediaseen today through various media outlets (television, movies, Internetcontent, etc.). These tools alloy, designers the ability to generate,compose, composite, and animate images and videos in a virtualthree-dimensional space.

A computer simulating the three-dimensional space is able to produce(i.e., render) an image of the space as seen from a particular point inthe space, looking in a particular direction with a particular field ofview. Some applications define a virtual camera at the particular pointthat is oriented in the particular direction and has properties thatdefine the particular field of view. Such a virtual camera can be movedaround the three-dimensional space, reoriented, and may have variousother properties that can be adjusted. The virtual camera is a userinterface tool that collectively represents the set of properties thatdefine the direction, angle of view, and other attributes for renderinga scene from a particular point of view in particular direction.

Virtual cameras have generally been defined as having a particular focalplane, a distance at which objects will appear in focus when the viewfrom the camera is rendered. However, users may desire the ability tomove the apparent focal plane of the virtual camera closer to or furtherfrom the camera in the context of a scene laid out in athree-dimensional space within an application. Users may also want to beable to render in focus a range of distances and expand or contract thisrange within the context of a scene. Accordingly, there is a need in theart for virtual cameras with highly modifiable focal properties.Furthermore, there is a need for user interface tools to enable easymodification of these focal properties.

SUMMARY OF THE INVENTION

Some embodiments of the invention provide novel user interface tools forrendering a particular region in a media-editing application from aparticular location, in a particular direction, within a particularfield of view. The media-editing application of some embodimentsprovides a set of tools for a user to define a three-dimensional spacethat includes two- and three-dimensional media objects (e.g., images,text, video clips, and other such objects). This application furtherprovides a set of user interface tools for viewing and controlling thefocal properties for rendering a particular region within the createdspace from a particular location, in a particular direction, within aparticular field of view.

This application further provides a user interface tool, referred to inthe discussion below as a virtual camera, to represent the location,direction, etc. from which the space is rendered. The virtual camera ofsome embodiments has a region of focus that is a two-dimensional region(e.g., a plane) or three-dimensional region (e.g., a volume) within theregion rendered by the virtual camera. In these embodiments, objectslocated in the region of focus are rendered in focus by the virtualcamera while special effects (e.g., blurring effects, coloring effects,etc.) are applied to objects outside the region of focus but within theregion rendered by the virtual camera.

Some embodiments provide novel tools for viewing and controlling focalproperties of the virtual camera, which can render a region from aparticular location, in a particular direction, within a particularfield of view. In some embodiments, the modifiable focal propertiesinclude the size of the region of focus, its distance from the camera,and the amount of effects applied to objects not within the region offocus. Some embodiments display the region of focus within thethree-dimensional space of the media-editing application, enabling auser to modify the region of focus of a virtual camera within thecontext of a scene rendered by the virtual camera.

Specific modifiable parameters in some embodiments are an aperture, afocus offset, a near focus, and a far focus. The aperture parameter ofsome embodiments enables a user to affect the extent to which specialeffects (e.g., blurring) are applied to objects not in the region offocus. The focus offset parameter of some embodiments allows a user tomove the region of focus closer to or further from the virtual camera.The near focus and far focus parameters of some embodiments allow a userto modify the size of the region of focus such that objects are in focusat more than one distance. Some embodiments also allow modification ofother focal properties.

Various embodiments provide various user interface tools, orcombinations of user interface tools, for adjusting the depth of fieldparameters. Sliders are one example of a user interface tool formodifying the aperture, focus offset, near focus, and far focus, as wellas other parameters. Another type of user interface tool is one thatprovides for direct numerical input of the parameters (e.g., as a numberof pixels, a percentage, etc.), either in conjunction with sliders orseparately. Some embodiments provide moveable planes within thethree-dimensional space of the media-editing application representingthe focus offset, near focus, and far focus.

In some embodiments, the planes that represent the focus offset, nearfocus, and far focus move whenever a user modifies the parameters with aslider, direct numerical input, or other user interface tool. In someembodiments, a user can select and drag the planes directly in order tomodify the depth of field parameters. The planes have handles that areused for dragging the planes in some embodiments. Some embodimentsprovide only one of the described controls for modifying the depth offield parameters, while other embodiments provide more than one of thedescribed controls, or other controls that are not mentioned.

Some embodiments enable a user to set the depth of field properties of avirtual camera to change over a determined duration. A user can input(via any of the methods described above) a starting set of depth offield properties and a finishing set of depth of field properties, aswell as a duration (e.g., length of time, number of frames of video,etc.) over which the parameters will change. When the scene is renderedfrom the point of view of the virtual camera, the depth of fieldproperties change over the determined duration, from the startingproperties to the finishing properties.

Some embodiments enable a user to select a target object to be broughtinto focus over the set duration. The user, in some embodiments, canselect the target object, the duration, and the method of transition(e.g., constant movement of region of focus, accelerated movement ofregion of focus, etc.). When the scene is rendered, the region of focuswill move from an initial distance from the camera to the distance ofthe target object from the camera, such that the target object is infocus at the end of the set duration.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purpose of explanation, several embodiments of theinvention are set forth in the following figures.

FIGS. 1-3 illustrate a simplified view of the modification of depth offield properties of a virtual camera of some embodiments.

FIG. 4 illustrates a three-dimensional compositing application of someembodiments.

FIG. 5 conceptually illustrates a process 500 of some embodiments forrendering an image from a virtual camera.

FIG. 6 illustrates a graph plotting the site of the circle of confusionagainst distance from a virtual camera of some embodiments.

FIGS. 7-14B illustrate the modification of depth of field properties ofa virtual camera via various user interface tools in a compositingapplication of some embodiments.

FIGS. 15-18 illustrate the use of handles along a camera frustum formodifying depth of field properties in some embodiments.

FIG. 19 conceptually illustrates a process of some embodiments fordefining a change in depth of field parameters in order to bring aparticular object into focus over a set duration.

FIGS. 20-22 illustrate the selection of a target object to be broughtinto focus in a compositing application of some embodiments.

FIG. 23 illustrates a perspective view of the first frame of a focusbehavior of some embodiments.

FIG. 24 illustrates a view rendered from a virtual camera of the firstframe of the focus behavior.

FIG. 25 illustrates a perspective view of the last frame of the focusbehavior.

FIG. 26 illustrates a view rendered from the virtual camera of the lastframe of the focus behavior.

FIG. 27 conceptually illustrates the software architecture of someembodiments of the compositing application.

FIG. 28 conceptually illustrates a computer system with which someembodiments of the invention are implemented.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous details are set forth for purposeof explanation. However, one of ordinary skill in the art will realizethat the invention may be practiced without the use of these specificdetails.

I. Overview

Some embodiments of the invention provide novel user interface tools forrendering a particular region in a media-editing (e.g., compositing)application from a particular location, in a particular direction,within a particular field of view. The media-editing application of someembodiments provides a set of tools for a user to define athree-dimensional space that includes two- and three-dimensional mediaobjects (e.g., images, text, video clips, and other such objects). Thisapplication further provides a user interface tool, referred to in thediscussion below as a virtual camera, to represent the location,direction, etc. from which the space is rendered.

This application further provides a user interface tool, referred to inthe discussion below as a virtual camera, to represent the location,direction, etc. from which the space is rendered. The virtual camera ofsome embodiments has a region of focus that is a two-dimensional region(e.g., a plane) or three-dimensional region (e.g., a volume) within theregion rendered by the virtual camera. In these embodiments, objectslocated in the region of focus are rendered in focus by the virtualcamera while special effects (e.g., blurring effects, coloring effects,etc.) are applied to objects outside the region of focus but within theregion rendered by the virtual camera.

Some embodiments provide novel tools for viewing and controlling focalproperties of the virtual camera, which can render a region from aparticular location, in a particular direction, within a particularfield of view. In some embodiments, the modifiable focal propertiesinclude the size of the region of focus, its distance from the camera,and the amount of effects applied to objects not within the region offocus. Some embodiments display the region of focus within thethree-dimensional space of the media-editing application, enabling auser to modify the region of focus of a virtual camera within thecontext of a scene rendered by the virtual camera.

Specific modifiable depth of field parameters in some embodiments are anaperture, a focus offset, a near focus, and a far focus. The apertureparameter of some embodiments enables a user to affect the extent towhich special effects (e.g., blurring) are applied to objects not in theregion of focus. The focus offset parameter of some embodiments allows auser to move the region of focus closer to or further from the virtualcamera. The near focus and far focus parameters of some embodimentsallow a user to modify the size of the region of focus such that objectsare in focus at more than one distance. Some embodiments also allowmodification of other depth of field parameters.

Some embodiments provide a display area that displays a virtual camera,the field of view of the virtual camera, and any objects to be renderedby the virtual camera. Some such embodiments provide planes in the fieldof view that represent the focus offset, near focus, and far focusparameters. FIG. 1 illustrates a simplified view of a virtual camera 105in a display area 100. Lines 110 represent the field of view or thevirtual camera. Within the field of view 110 are objects 111, 112, and113. Dashed lines 115 illustrate a plane showing the focal plane ofvirtual camera 105. When the scene shown in FIG. 1 is rendered from thevirtual camera 105, object 112 will appear in focus, while blurringeffects are applied to objects 111 and 113.

Various embodiments provide various user interface tools, orcombinations of user interface tools, for adjusting the depth of fieldparameters. Sliders are one example of a user interface tool formodifying the aperture, focus offset, near focus, and far focus, as wellas other parameters. Another type of user interface tool is one thatprovides for direct numerical input of the parameters (e.g., as a numberof pixels, a percentage, etc.), either in conjunction with sliders orseparately.

FIG. 1 also illustrates the sliders 120, 125, 130, and 135 of someembodiments used to modify depth of field parameters. In someembodiments, 120 is a slider for the focus offset, 125 is a slider forthe near focus, 130 is a slider for the far focus, and 135 is a sliderfor the aperture. The focus offset can be positive or negative in someembodiments, and accordingly is set at zero when centered on the sliderbar. In FIG. 1, the near focus and far focus parameters are set to zero,so the only plane that is in focus is at the focal plane 115. Theaperture is set at approximately the three-eighths mark, indicating thatobjects not in focus will be blurred a non-zero amount. In someembodiments, setting the aperture slider 135 to zero results in noblurring at all.

In some embodiments, the planes mentioned above that represent the focusoffset, near focus, and far focus move whenever a user modifies theparameters with a slider, direct numerical input, or other userinterface tool. In some embodiments, a user can select and drag theplanes directly in order to modify the depth of field parameters. Theplanes have handles that are used for dragging the planes in someembodiments. Some embodiments provide only one of the described controlsfor modifying the depth of field parameters, while other embodimentsprovide more than one of the described controls, or other controls thatare not mentioned.

FIG. 2 illustrates the scene from FIG. 1 after a user has modified thefocus offset with slider 120. Slider 120 has been moved to the right,which moves the apparent focal plane represented by dashed lines 215.When the scene shown in FIG. 2 is rendered from the virtual camera 105,object 113 will appear in focus, while blurring effects are applied toobjects 111 and 112. In some embodiments, object 111 will be blurredmore than object 112 because it is further from the apparent focal plane215.

FIG. 3 illustrates the scene from FIG. 1 after a user has modified thenear focus and far focus parameters with sliders 125 and 130, and theaperture parameter with slider 135. Slider 125 has been moved a smallamount, which moves the near focus plane 335 a short distance to theleft (closer to the camera). Slider 130 has been moved a larger amount,which moves the far focus plane substantially to the right (further fromthe camera). Furthermore, slider 135 has been moved a substantialamount, resulting in an increase in the aperture. When the scene shownin FIG. 3 is rendered from the virtual camera 105, objects 112 and 113will both appear to be in focus, while blurring effects are applied toobject 111. As a result of the increased aperture, object 111 will berendered as blurrier than if the aperture had not been changed.

Some embodiments enable a user to set the depth of field properties of avirtual camera to change over a specific duration. A user can input (viaany of the methods described above) a starting set of depth of fieldproperties and a finishing set of depth of field properties, as well asa duration (e.g., length of time number of frames of video, etc.) overwhich the parameters will change. When the scene is rendered from thepoint of view of the virtual camera, the depth of field propertieschange over the determined duration, from the starting properties to thefinishing properties. For example, a user could set the parameters suchthat the focus offset would move from the distance shown in FIG. 1 tothe distance shown in FIG. 2 over a set duration.

Some embodiments enable a user to select a target object to be broughtinto focus over the set duration. The user, in some embodiments, canselect the target object, the duration, and the method of transition(e.g., constant movement of region of focus, accelerated movement ofregion of focus, etc.). When rendered, the region of focus will movefrom an initial distance from the camera to the distance of the targetobject from the camera, such that the target object is in focus at theend of the set duration.

II. Compositing Application

FIG. 4 illustrates a three-dimensional compositing application 400provided by some embodiments. The compositing application 400 provides aprimary display area 405, an object selection area 410, a first set ofvirtual camera controls 415, a second set of virtual camera controls420, a preview display area 455, a set of control icons 425, and videorendering controls 430. Some embodiments provide other features, such asmultiple timelines indicating different camera behaviors.

The primary display area 405 includes objects 435, 440, and 445, as wellas camera 450. Each of the objects 435, 440, and 445 are in the field ofview of camera 450. Each of the objects 435-445 has a correspondingentry in the object selection area 410, as does the camera 450. Theprimary display area 405 is displaying a perspective view of the scenein FIG. 4. In some embodiments, the primary display area can alsodisplay the view from camera 450 (or other cameras that have beendefined). The primary display area 405 of some embodiments includesgridlines to assist a user in laying out a scene (e.g., to assist indetermining the distance from an object to a virtual camera).

The first set of camera controls 415 provides controls for camera 450.These controls allow a user to define the camera type and modify theangle of view for camera 450, as well as controls to move and rotate thecamera 450 within the scene shown in the display area 405. The first setof camera controls also displays the focal length of the camera (i.e.,the focal distance, the distance from the camera at which, without themodification of any depth of field parameters, the camera will renderobjects in focus.

The second set of camera controls 420 also provides controls for camera450. Some of the controls 420 provide the same abilities to a user ascontrols 415 (such as defining the camera type or modifying the angle ofview). Furthermore, the second set of camera controls 420 allows a userto modify depth of field properties of the camera 450 with sliders andnumerical input boxes 421-424. Sliders 421-424 will be described ingreater detail in Section III below. Some embodiments use different userinterface items for controls 420 rather than slider tools or directnumerical input.

Above the second set of camera controls 420 is a preview display 455 ofsome embodiments. The preview display 455 displays the view through thecamera 450. As objects 435-445 are moved in the primary display area, orproperties (e.g., depth of field parameters) of the camera 450 arechanged, the appearance of the preview display 455 will changeaccordingly.

The set of control icons 425 includes numerous icons for performingvarious functions within the compositing application. The set of controlicons 425 includes icon 426, which allows a user to define a new camera(e.g., camera 450). Icon 427 allows a user to define a new behavior foran object, camera, or other item. In some embodiments, a behavior is achange in some property (e.g., position, orientation, etc.) of a cameraor object over a period of time. Some embodiments allow a user to setbehaviors of a camera relating to the camera's depth of field (e.g.,bringing an object into focus).

III. Depth of Field Rendering

Some embodiments allow users to modify the depth of field parameters ofvirtual cameras in a compositing application. Doing so enables the userto adjust how objects in the field of view of a virtual camera appearwhen rendered (i.e., how in focus or blurred an object appears whenrendered). How an object appears when rendered by a virtual camera isaffected by the focal distance of the virtual camera and how objectsthat are not at the focal distance of the camera are blurred.

FIG. 5 illustrates a process 500 of some embodiments for renderingimages (e.g., frames of video) from a virtual camera. The process 500begins by determining (at 503) a first image to render. In someembodiments, the first image is the first frame of a scene. Sometimesthe first image is a frame that a user has selected to render first(e.g., by dragging an indicator on a timeline to a particular point inthe timeline indicating a particular frame).

After determining the image to render, the process 500 determines (at505) the depth of field parameters for the virtual camera. In someembodiments, the depth of field parameters are specific to theparticular image being rendered. For example, the parameters may changethroughout a scene of a video that includes of a number of images, andthe parameters must be determined for each particular image. In someembodiments, the image may be rendered as the user edits the depth offield parameters (or other properties, such as the location ororientation of the virtual camera rendering the image). The depth offield parameters of some embodiments include the region of focus (i.e.,the distance or distances at which objects will be rendered as infocus), and how the focus falls off for objects not at such distances.Such parameters are input by users through a variety of user interfacetools in some embodiments.

In some embodiments, the determination of the depth of field parametersincludes calculating the circle of confusion at all distances from thecamera. The circle of confusion is the size that a point appears as whenrendered. The compositing application of some embodiments, whenrendering image, displays each point as a disk, the size of which isdependent on how blurred the point is to appear. Points that are furtherfrom the apparent focal plane (i.e., the distance from the camera atwhich objects are rendered in focus) of the virtual camera will have alarger circle of confusion. FIG. 6 illustrates a graph 600. The graph600 plots the size of the circle of confusion on axis 610 against thedistance from the virtual camera on axis 605. Distances SN and SFrepresent the near and far ends of the range of distances in whichobjects will appear in focus. As objects at these distances are renderedas in focus, the circle of confusion (represented by dashed line 615) iszero from SN to SF. The dashed line illustrates the manner in which thecircle of confusion increases at distances not within the distances fromSN to SF. In some embodiments, a user can set parameters to affect therate at which the circle of confusion grows as objects get furtheroutside of the range in focus.

After determining the depth of field parameters, the process 500determines (at 510) the blurring algorithm to be used. Some embodimentsuse an algorithm that applies a defocus filter to a disk the size of thecircle of confusion. Some embodiments use algorithms that are lesscomputationally intensive than a defocus disk, such as a Gaussian filteror other algorithms. In some embodiments, a user may select betweendifferent blurring algorithms for rendering an image.

The process 500 then selects (at 515) a pixel in the image to berendered. Some embodiments start with a corner pixel, and traverseacross an entire row of pixels before moving to a second row. Otherembodiments start with a corner pixel, and traverse down an entirecolumn before moving to a second column. Other embodiments use otheralgorithms for traversing through all the pixels in an image.

Once a pixel is selected, the process 500 determines (at 520) thedistance of the pixel from the virtual camera. Each pixel effectivelyrepresents a ray emanating from the virtual camera at a particular angle(i.e., x degrees off of horizontal and y degrees off of vertical) orsmall range of angles. The distance at which the ray would firstintersect an object is the distance of the pixel. The process 500 thencalculates (at 525) the blurring around the pixel, based on the size ofthe circle of confusion at the pixel's distance and the blurringalgorithm determined at 510.

The process 500 then determines (at 530) whether there are more pixelsfor which the distance and blurring have not been calculated. If no morepixels remain, the process 500 proceeds to 535 to render the image. Ifmore pixels remain, the process returns to 515 and repeats 515 through530 until all pixels for the current image have been selected.

After rendering the image, the process 500 determines (at 540) whetherto continue rendering. If the process determines to continue rendering,the process moves to 545 to determine the next image. For example, if auser is playing back a scene, then the next frame in the scene is thenext image. After determining the next image to render, the processmoves to 505 and repeats 505 through 535 to render the new image.

If the process 500 determines (at 540) that no more images are to berendered, the process ends. For example, if the most recently renderedimage is the last frame in a video, the process would not have anyfurther images to render. Also, a user could select a user interfaceitem (e.g., a stop button) that would cause the process to stoprendering images.

A. User Interface Tools for Modifying Depth of Field Parameters

In some embodiments, the depth of field parameters of a virtual cameracan be modified by one or more sets of user interface tools. Asdiscussed above, the depth of field parameters affect the extent towhich objects in the field of view of the virtual camera will appear infocus when rendered by the virtual camera.

FIG. 7 illustrates a scene in a compositing application of someembodiments. FIG. 7 illustrates a virtual camera 705, and three objects710, 715, and 720, at different distances from the virtual camera. Thevirtual camera 705 and the objects 710-720 are shown in a primarydisplay area of the compositing application. The display area gives aperspective view of the scene and any virtual cameras that have beendefined, such as camera 705.

FIG. 8A illustrates the selection, by a user, of virtual camera 705. Insome embodiments, a user selects a virtual camera by clicking on thevirtual camera in the primary display area. In some embodiments, a userselects a virtual camera by clicking on the row for the camera in theobject selection area 820. A user can perform either of these methods,or other methods (e.g., shortcut keys) to select a virtual camera insome embodiments. FIG. 8A illustrates that row 815, the row for camera705, is highlighted, because camera 705 is selected.

The selection of a virtual camera also causes the display of viewingfrustum 805. Viewing frustum 805 shows a user what is in the field ofview of the virtual camera 705. Plane 810 illustrates the focal plane ofthe camera 705 (i.e., the plane at which objects will be rendered infocus). The focal plane is the entire region of focus at this point.

Selection of the virtual camera 705 also causes display of cameracontrols 825 in some embodiments. The camera controls of someembodiments include depth of field controls 830. FIG. 8B illustrates anenlarged view of the depth of field controls 830 from FIG. 8A. Theillustrated depth of field controls include four sliders 831, 832, 833,and 834. Slider 831 controls the aperture of the virtual camera, whichis used in some embodiments to determine how quickly the circle ofconfusion increases as objects are located further away from the focalplane (i.e., how blurry objects not in focus will be).

Slider 832 controls the focus offset. In some embodiments, the focusoffset measures the distance from the focal plane of the camera (i.e.,the distance at which objects are rendered in focus in the absence ofmodification of the depth of field properties of the camera) to theapparent focal plane. In other words, the focus offset allows the userto modify the apparent focal plane of the virtual camera withoutmodifying any other properties of the camera. Slider 833 controls thenear focus plane. Moving slider 833 to the right causes the near focusplane to move closer to the camera. The near focus plane, in someembodiments, represents the start of the region of focus (i.e., thedistance closest to the camera at which objects will be rendered ascompletely in focus). Slider 834 controls the far focus plane. Movingslider 834 to the right causes the far focus plane to move further fromthe camera. The far focus plane, in some embodiments, represents the endof the region of focus (i.e., the distance furthest from the camera atwhich objects will be rendered completely in focus).

In some embodiments (e.g., the depicted embodiments), next to each ofthe sliders 831-834 is a numerical input tool. Moving a slider willaffect the corresponding number in some embodiments. Furthermore, insome embodiments, the number can be changed directly, either by typingthe desired number or by selecting the right and left arrows on eitherside of the number to increase or decrease the number. Directly changingthe number will cause the corresponding slider to move accordingly insome embodiments. Also, directly changing the number will, ifappropriate, cause the focal plane, near focus plane, or far focus planeto move in the display area.

The number associated with slider 831 is a measurement, in someembodiments, of the aperture of the virtual camera. This measurement isgiven in millimeters in some embodiments. The focus offset measurement,associated with slider 832, is a distance in pixels from the focusoffset in some embodiments. The focus offset is set to zero when theslider is centered (as in FIGS. 8A and 8B), and moving the offset to theleft or right moves the apparent focal plane closer to or further fromthe camera, correspondingly.

For the near and far focus numerical measurements associated withsliders 833 and 834, some embodiments use percentages of the foregroundand background. Some embodiments define the foreground as the area inthe field of view between the near plane of the camera frustum and theapparent focal plane. Similarly, some embodiments define the backgroundas the area in the field of view between the apparent focal plane andthe far plane of the camera frustum. Thus, if the near focus slider isset to 0%, none of the area in front of the focal plane will be renderedin focus. If the near focus slider is set to 100%, the entire foregroundwill be rendered in focus. Similarly, if the far focus slider is set to100%, the entire background will be rendered in focus.

Some embodiments use only one slider to move both the near and far focussliders. In some embodiments, this slider measures a percentage of thebackground/foreground. Other embodiments use a single slider thatdirectly measures a distance (e.g., in units such as pixels) the nearand far focus planes should move, such that the two planes are alwaysequidistant from the apparent focal plane. Similarly, some embodimentsuse two sliders, as is shown in FIGS. 8A and 8B, but measure distances(e.g., in pixels in relation to the apparent focal plane) rather thanpercentages. Some embodiments allow a user to choose which of thedescribed sets of controls (or other control sets for controlling depthof field parameters) are provided by the compositing application.

In FIG. 8A, cursor 840 is over the far focus slider. FIG. 9A illustratesthe result of a user sliding the far focus slider to 47% with thecursor, as well as sliding the near focus slider to 57% (also using thecursor). FIG. 9B illustrates an enlarged view of the sliders from FIG.9A. FIG. 9A illustrates the appearance of near focus plane 933 and farfocus plane 934. The area between near focus plane 933 and far focusplane 934 (which includes objects 710 and 715) is the region of focus.Some embodiments display the objects as in or out of focus in theperspective view shown in the primary display area, whereas someembodiments save computational resources by only calculating theblurring of the objects upon rendering the scene from the virtualcamera.

FIG. 10 illustrates a compositing application 1000 of some embodiments,with three objects 1010, 1015, and 1020, along with virtual camera 1025,in the display area 1005. The display area illustrates the objects froma different perspective than in FIGS. 7-9A. The compositing application1000 also includes a set of camera controls 1030, including depth offield sliders 1031 (aperture), 1032 (focus offset), 1033 (near focus),and 1034 (far focus).

FIG. 11A illustrates the scene from FIG. 10 with the focus offset set to239 (in units of pixels, though some embodiments use different units asmentioned above), the near focus set to 35% and the far focus set to 38%(in percentages, though some embodiments measure the near and far focusdifferently, as mentioned above). FIG. 11B illustrates an enlarged viewof the sliders from FIG. 11A. Focus offset plane 1132, near focus plane1133, and far focus plane 1134 have also appeared as the correspondingparameter values are set to nonzero numbers. In FIG. 11A, a cursor 1140is over the right arrow on the numerical input for the focus offsetslider. A user using a selection tool (e.g., a mouse button) with thecursor located over this arrow will increase the focus offset in someembodiments. Similarly, selecting the left arrow will decrease the focusoffset.

FIG. 12A illustrates the scene after the user has used the right arrowon the focus offset numerical input to increase the focus offset from239 pixels to 627 pixels. Doing so has caused plane 1132 to moveaccordingly in the display area, and slider 1032 to move to the right.The user has also (via the slider, numerical input, or other method)increased both the near and far focus sliders. FIG. 12B illustrates anenlarged view of the sliders from FIG. 12A. Whereas in FIG. 11A, onlyobject 1015 was within the range of focus, in FIG. 12A objects 1010,1015, and 1020 are all within the range of focus, and thus would all berendered in focus.

FIG. 12A also illustrates cursor 1140 over the edge of far focus plane1134. In some embodiments, a user can drag a plane directly in order tochange the depth of field parameter associated with that plane. In someembodiments, the planes can only be dragged within a particular range.For example, the near focus plane 1133 in some embodiments cannot bemoved so that it is further from the virtual camera than the focusoffset plane 1132. Similarly, the far focus plane 1134 in someembodiments cannot be moved so that it is closer to the virtual camerathan the focus offset plane 1132.

In some embodiments, the focus offset plane 1132 can only be moved sothat it stays in between the near and far focus planes 1133 and 1134.However, in other embodiments, the focus offset plane 1132 can be movedoutside the range defined by the near and far focus planes 1133 and1134. When the focus offset plane is moved even with either the near orfar focus plane, the near or far focus plane disappears and the focusoffset plane can continue to move in that direction. In some suchembodiments, in which the near and far focus are defined by percentages,moving the focus offset plane causes the numerical percentages andsliders for the near and far focus planes to change such that the nearand far focus planes remain static. In other embodiments that define thenear and far focus planes with percentages, moving the focus offsetplane causes the near and far focus planes to move such that thenumerical percentages and sliders for the near and far focus planesremain static.

FIG. 13A illustrates that the far focus plane 1134 has been dragged bythe user (using the cursor 1140) such that it is closer to the focusoffset plane 1132 as compared with FIG. 12A. Doing so has caused the farfocus slider 1034 to move and the numerical value for the far focus tochange from 51% to 11%. FIG. 13B illustrates an enlarged view of thesliders. The user has also moved the near focus plane such that object1010 is no longer in the range that will be rendered as in focus. In thedepicted embodiment, the user could have moved the near focus plane 1133by moving the slider 1033, by using the numerical input, or by draggingthe near focus plane 1133 in the display area.

FIG. 13A also illustrates cursor 1140 over near focus plane 1133. FIG.14A illustrates that the near focus plane 1133 has been moved by theuser significantly closer to focal offset plane 1132. This has created asmall range of focus that only encompasses object 1015 and not muchelse. Moving the near focus plane 1133 also has caused the slider 1033to move and the near focus numerical value to change from 44% to 14%.FIG. 14B illustrates an enlarged view of the sliders.

The compositing application of some embodiments, rather than displayingthe focal offset, near focus, and far focus planes in the display area,displays handles along the camera frustum. FIG. 15 illustrates a virtualcamera 1505 with camera frustum 1510 and focal plane 1515. Focal plane1515 is the “physical” focal plane of the camera, representing thedistance that would be in focus with no changes to the focus offset,near focus, or far focus parameters. FIG. 15 also illustrates three setsof handles along the camera frustum. These handles are used in someembodiments to display and move the focus offset (handles 1520), nearfocus (handles 1525), and far focus (handles 1530) planes, therebyaffecting the depth of field for the virtual camera. For the sake ofclarity, only two handles from each of the three sets are labeled inFIG. 15.

FIG. 16 illustrates a cursor 1605 over one of the near focus handles1525. When a user selects the near focus handle 1525, near focus plane1625 appears. In some embodiments, the near focus plane 1625 onlyappears when one of the near focus handles 1525 is selected. The usercan then drag the near focus plane 1625 either closer to or further fromthe virtual camera 1505. Selecting one of the handles 1525 and draggingthe plane 1625 causes all four handles 1525 to move in some embodiments.

FIG. 17 illustrates the cursor 1605 over one of the focus offset handles1520. When a user selects the focus offset handle 1520, focus offsetplane 1720 appears. In some embodiments, the focus offset plane 1720only appears when one of the focus offset handles 1520 is selected. Theuser can then drag the focus offset plane 1720 either closer to orfurther from the virtual camera 1505. Selecting one of the handles 1520and dragging the plane 1720 causes all four handles 1520 to move in someembodiments.

FIG. 18 illustrates the cursor 1605 over one of the far focus handles1530. When a user selects the far focus handle 1530, far focus plane1830 appears. In some embodiments, the far focus plane 1830 only appearswhen one of the far focus handles 1530 is selected. The user can thendrag the far focus plane either closer to or further from the virtualcamera 1505. Selecting one of the handles 1530 and dragging the plane1830 causes all four handles 1530 to move in some embodiments.

Some embodiments incorporate the handles shown in FIG. 15 into acompositing application such as that illustrated in FIG. 8A, along withother controls to affect depth of field parameters such as sliders831-834 and other inputs. In some such embodiments, the sliders andother inputs are affected by the movement of the handles in the same wayas they are affected by movement of the depth of field planes, describedabove.

B. Rendering Changes in Depth of Field Parameters Over Time

Some embodiments enable a user to set the depth of field parameters of avirtual camera to change over a determined duration. A user can input astarting set of depth of field parameters and a finishing set of depthof field parameters, as well as a duration (e.g., length of time, numberof frames of video, etc.) over which the parameters will change. In someembodiments, the user can input the starting and finishing sets of depthof field parameters with the user interface items (sliders, draggingplanes or handles along the camera frustum, numerical input) describedabove.

When the scene portrayed by the virtual camera is rendered, the depth offield parameters change over the determined duration, from the startingparameters to the finishing parameters. For example, a user could setthe parameters such that the focus offset and near and far focus wouldstart as shown in FIG. 8, in which all three parameters are set to zero(only one plane is in focus, and it is at the physical focal plane ofthe camera), and end as shown in FIG. 9 (in which the near and far focusplanes are a substantial distance from the focal plane). When renderedas a video over the set duration, the video will start with all threeobjects blurry to some degree, and finish with objects 710 and 715completely in focus and object 720 less blurry than at the start of thevideo.

Some embodiments enable a user to select a target object to be broughtinto focus over a set duration. The user, in some embodiments, canselect the target object, the duration, and the method of transition(e.g., constant movement of focus offset, accelerated movement of focusoffset, etc.). When rendered, the apparent focal distance of the camera(i.e., the distance at which objects are in focus) will move from aninitial distance to the distance of the target object, such that thetarget object is in focus at the end of the set duration.

FIG. 19 conceptually illustrates a process 1900 of some embodiments fordefining a change in depth of field parameters in order to bring aparticular object into focus over a set duration. The process 1900starts when input is received (at 1905) selecting a focus behavior aparticular virtual camera.

At 1915, the process 1900 receives a selection of a target object. FIGS.21 and 22 illustrate the selection of object 2105 as the target objectfor the selected focus camera behavior. FIG. 21 illustrates a userdragging object 2105 with cursor 2005 into the target box 2110. In someembodiments, the user clicks on the object from the object selectionarea 2025 and drags it into target box 2110 in order to select theobject as the object upon which the camera will focus. In someembodiments, a user can select the object in the display view in orderto move the object into the target box. Other embodiments use differentmethods of selecting an object (e.g., methods that do not use a targetbox as depicted in FIG. 21).

After receiving the selection of a focus behavior for a particularvirtual camera, the process 1900 provides (at 1910) options for thefocus behavior. FIG. 20 illustrates that two sets of controls areprovided, a moveable set of controls 2015 and a fixed set of controls2020. In the depicted embodiment, each of the two sets of controls 2015and 2020 provides three user interface items with which a user caninteract in order to define the camera focus behavior. FIG. 20illustrates a target user interface item 2021 that indicates a targetobject of the behavior (that is, the object upon which the camera willfocus), a slider 2022 to set the transition time of the behavior (thatis, to select when during the overall duration of the behavior theobject will be brought into focus), and a drop-down menu 2023 with whicha user can select the transition method (how the focal plane will movefrom its starting position to the target object).

Selecting a focus behavior also causes the provision of an object 2030for the focus behavior in the object selection area 2025. The focusbehavior object 2030 is a sub-object of the camera with which it isassociated. In some embodiments, after initially entering settings forthe focus behavior, a user can select the focus behavior object 2030 inorder to bring up the behavior controls 2015 and 2020 so that thesettings can be adjusted.

At 1915, the process 1900 receives a selection of a target object. FIGS.21 and 22 illustrate the selection of object 2105 as the target objectfor the selected focus camera behavior. FIG. 21 illustrates a userdragging object 2105 with cursor 2005 into the target box 2110. In someembodiments, the user clicks on the object from the object selectionarea 2030 and drags it into target box 2110 in order to select theobject as the object upon which the camera will focus. In someembodiments, a user can select the object in the display view in orderto move the object into the target box. Other embodiments use differentmethods of selecting an object (e.g., methods that do not use a targetbox as depicted in FIG. 21).

In some embodiments, the target object may be either within the field ofview of the camera or not within the field of view of the camera. If theobject is not within the field of view of the camera, then in someembodiments, the behavior will move the focal plane to the distance ofthe target object. Some embodiments do not allow the target object to beout of the field of view of the camera. Other embodiments allow thetarget object to be out of the field of view, but rotate the cameraduring the behavior so that the object is within the field of view.

FIG. 22 illustrates the compositing application after the object 2105has been successfully dragged into target box 2110. A small version ofthe object 2105 is displayed in the target box 2110 (and in the targetbox in the moveable set of controls 2015), and the name of the object(“lift-off”, for object 2105) is displayed next to both target boxes.This indicates that at the end of the duration for the behavior, theapparent focal plane of the camera will be located at the depth of theselected object 2105.

At 1920, the process receives a duration for the behavior. Differentembodiments provide different user interface tools for a user to set theduration. In some embodiments, a window pops up when a user selects afocus behavior, asking the user to input a duration for the behavior. Insome embodiments, a user adjusts timeline 2035 located below the displayarea to set the duration for the behavior. In FIG. 20, timeline 2035 isset for 300 frames, the entirety of the scene. In some embodiments, auser can select the end of the timeline 2035 and drag it left or rightto set the duration for the behavior. The starting point for thebehavior can also be changed by dragging the left end of the timeline tothe right, such that the behavior does not begin at the start of thescene. The scene length can be changed in some embodiments by alteringthe number of frames using user interface item 2040.

At 1925, the process receives a selection of transition options. In someembodiments, these are the transition time and transition method. InFIG. 20, either transition time slider 2022 can be used to set thepercentage of the overall duration (set at 1920) during which the focalplane will actually be moving between its initial distance and thedistance of the target object. In some embodiments, the transition timecan also be input directly as a numerical percentage value, as shown incontrols 2020, or with other user interface tools.

FIG. 20 also illustrates drop-down menus 2023 labeled “speed”, each ofwhich allows the selection of a transition method that defines how thefocal plane moves from its initial position to the target object. Insome embodiments, the different options include at least one of constant(the focal plane moves at a uniform speed), ease in (the focal planestarts slowly and works up to a uniform speed), ease out (the focalplane starts at a uniform speed and slows down as it approaches thetarget object, ease in and out (a combination of the two above),accelerate (the focal plane moves at an increasing velocity untilreaching the target object), and decelerate (the focal plane moves at adecreasing velocity until reaching the target object). After 1925, theprocess has received all the information to define the behavior, andtherefore ends.

In the process 1900, the process receives a selection of a targetobject, then a duration for the behavior, then the selection oftransition options. In some embodiments, the order in which these arereceived is different. For instance, in some embodiments a user willinput the duration before selecting a target object, or will input thetransition options prior to either inputting the duration or selectingthe target object. Furthermore, in some embodiments, the user can editthese options afterwards to redefine the behavior. For example, a usercan modify the transition method if, after rendering the scene thatincludes the behavior, the user decides that the focal offset shouldmove in a different way from the initial position to the target object.Some embodiments even allow a user to modify the transition optionswhile rendering the scene.

In some embodiments, a user can render a scene including a focusbehavior (e.g., by clicking on the play button 2045). Some embodimentsrender the entire scene, even if the behavior has a duration less thanthe length of the time. Some embodiments also enable a user to onlyrender the scene for the duration of the behavior rather than for thelength of the entire scene (e.g., with a play button specific to thebehavior timeline 2035).

FIG. 23 illustrates a perspective view of the scene from FIG. 20 atframe 1, with the apparent focal plane at its initial position. In someembodiments, a user can select and drag time mark 2310 to movethroughout the scene. In FIG. 23, time mark 2310 is at the start of thescene, frame 1. FIG. 24 illustrates the rendered view at frame 1 fromthe virtual camera 2007. As can be seen in FIG. 24, objects 2105 (thetarget object) and 2415 are blurry, whereas object 2420 is in focus.

FIG. 25 illustrates a perspective view of the scene at frame 300 (thefinal frame in the scene). Time mark 2310 has been moved to the end ofthe timeline (either by the application playing the entire scene, or bya user dragging the mark to the end of the timeline). The focus offsetplane is now at the distance of the target object, object 2105, and thenear focus and far focus planes have moved along with the focus offsetplane. In some embodiments, the distances of the near and far focusplanes from the focus offset plane stay constant. In other embodiments,the distances vary as the percentages (defined by the sliders asdescribed above) stay constant. FIG. 26 illustrates the rendered view atframe 300 from the virtual camera 2007. As compared to the view at frame1 (FIG. 24), object 2415 is even blurrier, object 2105 has becomeblurry, and object 2420 is now in focus.

While the described embodiments uses a behavior to move the focus offset(apparent focal plane) to a target object, some embodiments allow forother behaviors to be specified. For example, in some embodiments, anobject can be selected such that the object will be brought to the focalplane of a virtual camera over a set duration. Some embodiments allow auser to specify a behavior that moves the near or far focus plane suchthat a target object is brought into the region of focus.

IV. Software Architecture

In some embodiments, the compositing application described above isimplemented as a set of modules. FIG. 27 conceptually illustrates thesoftware architecture of some embodiments of the compositingapplication. In some embodiments, the compositing application is astand-alone application or is integrated into another application, whilein other embodiments the application might be implemented within anoperating system. FIG. 27 illustrates a cursor driver 2705, a displaymodule 2710, a user interface (UI) interaction module 2715, a depth offield calculation module 2720, and a rendering engine 2725.

In some embodiments, as illustrated, the cursor driver and/or displaymodule are part of an operating system 2730 even when the compositingapplication is a stand-alone application separate from the operatingsystem. The UI interaction module 2715 generates user interface items,such as the depth of field sliders and planes described above, anddetermines how they should be displayed within the compositingapplication. The UI interaction module 2715 passes this information tothe display module 2710, which enables the display of the compositingapplication, including the user interface items, on a computer monitoror other such display device (not shown).

A user interacts with the user interface items via input devices (notshown). The input devices, such as cursor controllers, send signals tothe cursor roller driver 2705, which translates those signals into userinput data that is provided to the UI interaction module 2715. The UIinteraction module 2715 uses the user input data to modify the displayeduser interface items. For example, if a user drags a cursor along a nearfocus slider, the UI interaction module 2715 will instruct the displaymodule to move the slider on the display, and to move the near focusplane as well. The UI interaction module 2715 also passes data on userinteractions affecting depth of field parameters to the depth of field(DOF) calculation module 2720.

DOF calculation module 2720 calculates how in focus or blurry objectsshould appear when rendered. The DOF calculation module 2720 bases thisinformation on the distances of the objects from a particular virtualcamera, depth of field parameters (e.g., focal plane of the virtualcamera, aperture, focus offset, near and far focus distances) for thevirtual camera, the blurring algorithm selected, etc. In someembodiments, the DOF calculation module is one of a number of modulesthat apply special effects (i.e., any effect applied to a region in aspace that modifies the appearance of the affected region, such asblurring or coloring effects) to a region within the field of view ofthe virtual camera.

The DOF calculation module 2720 passes the DOF calculations to therendering engine 2725. The rendering engine 2725 enables the output ofaudio and video from the compositing application. The rendering engine2725, based on information from the DOF calculation module 2720 andother modules (not shown) sends information about how to display eachpixel of a scene to the display module 2710.

While many of the features have been described as being performed by onemodule (e.g., the UI interaction module 2715 or DOF calculation moduleC320), one of ordinary skill would recognize that the functions might besplit up into multiple modules, and the performance of one feature mighteven require multiple modules.

V. Computer System

Computer programs for implementing some embodiments are executed oncomputer systems. FIG. 28 illustrates a computer system with which someembodiments of the invention are implemented. Such a computer systemincludes various types of computer readable media and interfaces forvarious other types of computer readable media. Computer system 2800includes a bus 2805, a processor 2810, a graphics processing unit (GPU)2820, a system memory 2825, a read-only memory 2830, a permanent storagedevice 2835, input devices 2840, and output devices 2845.

The bus 2805 collectively represents all system, peripheral, and chipsetbuses that communicatively connect the numerous internal devices of thecomputer system 2800. For instance, the bus 2805 communicativelyconnects the processor 2810 with the read-only memory 2830, the GPU2820, the system memory 2825, and the permanent storage device 2835.

From these various memory units, the processor 2810 retrievesinstructions to execute and data to process in order to execute theprocesses of the invention. Some instructions are passed to and executedby the GPU 2820. The GPU 2820 can offload various computations orcomplement the image processing provided by the processor 2810. In someembodiments, such functionality can be provided using CoreImage's kernelshading language.

The read-only (ROM) 2830 stores static data and instructions that areneeded by the processor 2810 and other modules of the computer system.The permanent storage device 2835, on the other hand, is aread-and-write memory device. This device is a non-volatile memory unitthat stores instructions and data even when the computer system 2800 isoff. Some embodiments of the invention use a mass-storage device (suchas a magnetic or optical disk and its corresponding disk drive) as thepermanent storage device 2835.

Other embodiments use a removable storage device (such as a floppy disk,flash drive, or ZIP® disk, and its corresponding disk drive) as thepermanent storage device. Like the permanent storage device 2835, thesystem memory 2825 is a read-and-write memory device. However, unlikestorage device 2835, the system memory is a volatile read-and-writememory, such a random access memory. The system memory stores some ofthe instructions and data that the processor needs at runtime. In someembodiments, the invention's processes are stored in the system memory2825, the permanent storage device 2835, and/or the read-only memory2830.

The bus 2805 also connects to the input and output devices 2840 and2845. The input devices enable the user to communicate information andselect commands to the computer system. The input devices 2840 includealphanumeric keyboards and pointing devices (also called “cursor controldevices”). The output devices 2845 display images generated by thecomputer system. For instance, these devices display a GUI. The outputdevices include printers and display devices, such as cathode ray tubes(CRT) or liquid crystal displays (LCD).

Finally, as shown in FIG. 28, bus 2805 also couples computer 2800 to anetwork 2865 through a network adapter (not shown). In this manner, thecomputer can be a part of a network of computers (such as a local areanetwork (“LAN”), a wide area network (“WAN”), or an Intranet, or anetwork of networks, such as the internet. For example, the computer2800 may be coupled to a web server (network 2865) so that a web browserexecuting on the computer 2800 can interact with the web server as auser interacts with a GUI that operates in the web browser.

Any or all components of computer system 2800 may be used in conjunctionwith the invention. For instance, in some embodiments the execution ofthe frames of the rendering is performed by the GPU 2820 instead of theCPU 2810. Similarly, other image editing functions can be offloaded tothe GPU 2820 where they are executed before the results are passed backinto memory or the processor 2810. However, a common limitation of theGPU 2820 is the number of instructions that the GPU 2820 is able tostore and process at any given time. Therefore, some embodiments adaptinstructions for implementing processes so that these processes fit ontothe instruction buffer of the GPU 2820 for execution locally on the GPU2820. Additionally, some GPUs 2820 do not contain sufficient processingresources to execute the processes of some embodiments and therefore theCPU 2810 executes the instructions. One of ordinary skill in the artwould appreciate that any other system configuration may also be used inconjunction with the present invention.

As mentioned above, the computer system 2800 may include any one or moreof a variety of different computer-readable media. Some examples of suchcomputer-readable media include RAM, ROM, read-only compact discs(CD-ROM), recordable compact discs (CD-R), rewritable compact discs(CD-RW), read-only digital versatile discs (DVD-ROM), a variety ofrecordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.), flashmemory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magneticand/or solid state hard drives, ZIP® disks, and floppy disks.

While the invention has been described with reference to numerousspecific details, one of ordinary skill in the art will recognize thatthe invention can be embodied in other specific forms without departingfrom the spirit of the invention. For example, the application ofblurring effects to regions outside a region of focus has been describedin detail, but other special effects (i.e., any effect applied to aregion in a space that modifies the appearance of the affected region,such as blurring or coloring effects). Thus, one of ordinary skill inthe art would understand that the invention is not to be limited by theforegoing illustrative details, but rather is to be defined by theappended claims.

What we claim:
 1. A method comprising: presenting a display area fordisplaying a scene comprising media objects in a media-editingapplication; presenting a camera user interface (UI) tool within thedisplay area to represent a particular field of view from which torender the scene; receiving a first command to modify one or more of aset of depth of field parameters of the camera UI tool, the set of depthof field parameters comprising at least one of: a focus offset, a nearfocus, and a far focus; receiving a second command comprising selectionof a target object for a focus behavior for the particular field ofview; and rendering a video of the scene, focusing on the target objectfrom a perspective of a virtual camera having the particular field ofview, in accordance with the first command and the second command. 2.The method as recited in claim 1, wherein the first command comprisesselection of a starting set of depth of field properties, a finishingset of depth of field parameters, and selection of a set duration formodifying the one or more of the set of depth of field parameters of thecamera UI tool, and wherein the focus behavior is modified in accordancewith the first command and the second command for the set duration. 3.The method as recited in claim 2, wherein receiving the second commandcomprises receiving selection of the target object to render in focus atan end of the set duration measured as a length of time.
 4. The methodas recited in claim 1, wherein the camera UI tool has an apparent focalplane, and wherein rendering the video comprises moving the apparentfocal plane to a distance of the target object.
 5. The method as recitedin claim 4, further comprising providing a slider to receive input of atransition time specifying a moment when the target object is broughtinto focus.
 6. The method as recited in claim 1, wherein receiving thefirst command comprises receiving a selection of a rate at which the oneor more depth of field parameters is modified.
 7. The method as recitedin claim 1, wherein receiving the first command comprises receiving arequest to expand or contract a depth of field of the virtual camera. 8.A non-transitory computer-readable medium including one or moresequences of instructions that, when executed by one or more processors,causes: presenting a display area for displaying a scene comprisingmedia objects in a media-editing application; presenting a camera userinterface (UI) tool within the display area to represent a particularfield of view from which to render the scene; receiving a first commandto modify one or more of a set of depth of field parameters of thecamera UI tool, the set of depth of field parameters comprising at leastone of: a focus offset, a near focus, and a far focus; receiving asecond command comprising selection of a target object for a focusbehavior for the particular field of view; and rendering a video of thescene, focusing on the target object from a perspective of a virtualcamera having the particular field of view, in accordance with the firstcommand and the second command.
 9. The non-transitory computer-readablemedium as recited in claim 8, wherein the first command comprisesselection of a starting set of depth of field properties, a finishingset of depth of field parameters, and selection of a set duration formodifying the one or more of the set of depth of field parameters of thecamera UI tool, and wherein the focus behavior is modified in accordancewith the command for the set duration.
 10. The non-transitorycomputer-readable medium as recited in claim 9, wherein receiving thesecond command comprises receiving selection of the target object torender in focus at an end of the set duration measured as a length oftime.
 11. The non-transitory computer-readable medium as recited inclaim 8, wherein the camera UI tool has an apparent focal plane, andwherein rendering the video comprises moving the apparent focal plane toa distance of the target object.
 12. The non-transitorycomputer-readable medium as recited in claim 11, wherein the one or moresequences of instructions further cause providing a slider to receiveinput of a transition time specifying a moment when the target object isbrought into focus.
 13. The non-transitory computer-readable medium asrecited in claim 8, wherein receiving the first command comprisesreceiving a selection of a rate at which the one or more depth of fieldparameters is modified.
 14. The non-transitory computer-readable mediumas recited in claim 8, wherein receiving the first command comprisesreceiving a request to expand or contract a depth of field of thevirtual camera.
 15. A system comprising: one or more processors; and anon-transitory computer-readable medium including one or more sequencesof instructions that, when executed by the one or more processors,causes: presenting a display area for displaying a scene comprisingmedia objects in a media-editing application; presenting a camera userinterface (UI) tool within the display area to represent a particularfield of view from which to render the scene; receiving a first commandto modify one or more of a set of depth of field parameters of thecamera UI tool, the set of depth of field parameters comprising at leastone of: a focus offset, a near focus, and a far focus; receiving asecond command comprising selection of a target object for a focusbehavior for the particular field of view; and rendering a video of thescene, focusing on the target object from a perspective of a virtualcamera having the particular field of view, in accordance with the firstcommand and the second command.
 16. The system as recited in claim 15,wherein the first command comprises selection of a starting set of depthof field properties, a finishing set of depth of field parameters, andselection of a set duration for modifying the one or more of the set ofdepth of field parameters of the camera UI tool, and wherein the focusbehavior is modified in accordance with the first command and the secondcommand for the set duration.
 17. The system as recited in claim 16,wherein receiving the second command comprises receiving selection ofthe target object to render in focus at an end of the set durationmeasured as a length of time.
 18. The system as recited in claim 15,wherein the camera UI tool has an apparent focal plane, whereinrendering the video comprises moving the apparent focal plane to adistance of the target object, and wherein the one or more sequences ofinstructions further cause providing a slider to receive input of atransition time specifying a moment when the target object is broughtinto focus.
 19. The system as recited in claim 15, wherein receiving thefirst command comprises receiving a selection of a rate at which the oneor more depth of field parameters is modified.
 20. The system as recitedin claim 15, wherein receiving the first command comprises receiving arequest to expand or contract a depth of field of the virtual camera.